[Campbell Biology P.989] Based on Figure 42.21 and its descriptions, which of the following ... | Practice Question

Based on Figure 42.21 and its descriptions, which of the following statements correctly describe the diversity of gills and gas exchange mechanisms in aquatic animals?

  • A: The parapodia of a marine worm serve dual functions as gills for gas exchange and appendages for locomotion.
  • B: Crayfish possess long, feathery gills protected by an exoskeleton, and specialized appendages facilitate water flow over these surfaces.
  • C: Sea star gills are simple tubular projections of the skin, where gas exchange occurs by diffusion and coelomic fluid circulation aids gas transport.
  • D: All animals shown in the figure primarily rely on external water currents passively flowing through their internal gill structures for gas transport.
  • E: The tube feet of a sea star are solely for locomotion and play no role in gas exchange.

Explanation

Options A, B, and C are directly supported by the descriptions in Figure 42.21. Marine worm parapodia serve both as gills and for locomotion. Crayfish have feathery gills protected by the exoskeleton, and specialized appendages drive water flow. Sea star gills are simple skin projections, and their coelomic fluid aids gas transport, with tube feet also contributing to gas exchange. Option D is incorrect; while some might use passive flow, crayfish actively drive water, and sea stars use coelomic fluid circulation. Option E is incorrect as the caption for sea stars explicitly states that 'The tube feet surfaces also function in gas exchange.'